268 lines
8.7 KiB
C++
268 lines
8.7 KiB
C++
/*
|
|
* Copyright (c) 2014, Oculus VR, Inc.
|
|
* All rights reserved.
|
|
*
|
|
* This source code is licensed under the BSD-style license found in the
|
|
* LICENSE file in the root directory of this source tree. An additional grant
|
|
* of patent rights can be found in the PATENTS file in the same directory.
|
|
*
|
|
*/
|
|
|
|
/// \file
|
|
/// \brief \b [Internal] Passes queued data between threads using a circular buffer with read and write pointers
|
|
///
|
|
|
|
|
|
|
|
#ifndef __SINGLE_PRODUCER_CONSUMER_H
|
|
#define __SINGLE_PRODUCER_CONSUMER_H
|
|
|
|
#include "RakAssert.hpp"
|
|
|
|
static const int MINIMUM_LIST_SIZE=8;
|
|
|
|
#include "RakMemoryOverride.hpp"
|
|
#include "Export.hpp"
|
|
|
|
/// The namespace DataStructures was only added to avoid compiler errors for commonly named data structures
|
|
/// As these data structures are stand-alone, you can use them outside of RakNet for your own projects if you wish.
|
|
namespace DataStructures
|
|
{
|
|
/// \brief A single producer consumer implementation without critical sections.
|
|
template <class SingleProducerConsumerType>
|
|
class RAK_DLL_EXPORT SingleProducerConsumer
|
|
{
|
|
public:
|
|
// Constructor
|
|
SingleProducerConsumer();
|
|
|
|
// Destructor
|
|
~SingleProducerConsumer();
|
|
|
|
/// WriteLock must be immediately followed by WriteUnlock. These two functions must be called in the same thread.
|
|
/// \return A pointer to a block of data you can write to.
|
|
SingleProducerConsumerType* WriteLock(void);
|
|
|
|
/// Call if you don't want to write to a block of data from WriteLock() after all.
|
|
/// Cancelling locks cancels all locks back up to the data passed. So if you lock twice and cancel using the first lock, the second lock is ignored
|
|
/// \param[in] cancelToLocation Which WriteLock() to cancel.
|
|
void CancelWriteLock(SingleProducerConsumerType* cancelToLocation);
|
|
|
|
/// Call when you are done writing to a block of memory returned by WriteLock()
|
|
void WriteUnlock(void);
|
|
|
|
/// ReadLock must be immediately followed by ReadUnlock. These two functions must be called in the same thread.
|
|
/// \retval 0 No data is availble to read
|
|
/// \retval Non-zero The data previously written to, in another thread, by WriteLock followed by WriteUnlock.
|
|
SingleProducerConsumerType* ReadLock(void);
|
|
|
|
// Cancelling locks cancels all locks back up to the data passed. So if you lock twice and cancel using the first lock, the second lock is ignored
|
|
/// param[in] Which ReadLock() to cancel.
|
|
void CancelReadLock(SingleProducerConsumerType* cancelToLocation);
|
|
|
|
/// Signals that we are done reading the the data from the least recent call of ReadLock.
|
|
/// At this point that pointer is no longer valid, and should no longer be read.
|
|
void ReadUnlock(void);
|
|
|
|
/// Clear is not thread-safe and none of the lock or unlock functions should be called while it is running.
|
|
void Clear(void);
|
|
|
|
/// This function will estimate how many elements are waiting to be read. It's threadsafe enough that the value returned is stable, but not threadsafe enough to give accurate results.
|
|
/// \return An ESTIMATE of how many data elements are waiting to be read
|
|
int Size(void) const;
|
|
|
|
/// Make sure that the pointer we done reading for the call to ReadUnlock is the right pointer.
|
|
/// param[in] A previous pointer returned by ReadLock()
|
|
bool CheckReadUnlockOrder(const SingleProducerConsumerType* data) const;
|
|
|
|
/// Returns if ReadUnlock was called before ReadLock
|
|
/// \return If the read is locked
|
|
bool ReadIsLocked(void) const;
|
|
|
|
private:
|
|
struct DataPlusPtr
|
|
{
|
|
DataPlusPtr () {readyToRead=false;}
|
|
SingleProducerConsumerType object;
|
|
|
|
// Ready to read is so we can use an equality boolean comparison, in case the writePointer var is trashed while context switching.
|
|
volatile bool readyToRead;
|
|
volatile DataPlusPtr *next;
|
|
};
|
|
volatile DataPlusPtr *readAheadPointer;
|
|
volatile DataPlusPtr *writeAheadPointer;
|
|
volatile DataPlusPtr *readPointer;
|
|
volatile DataPlusPtr *writePointer;
|
|
unsigned readCount, writeCount;
|
|
};
|
|
|
|
template <class SingleProducerConsumerType>
|
|
SingleProducerConsumer<SingleProducerConsumerType>::SingleProducerConsumer()
|
|
{
|
|
// Preallocate
|
|
readPointer = RakNet::OP_NEW<DataPlusPtr>( _FILE_AND_LINE_ );
|
|
writePointer=readPointer;
|
|
readPointer->next = RakNet::OP_NEW<DataPlusPtr>( _FILE_AND_LINE_ );
|
|
int listSize;
|
|
#ifdef _DEBUG
|
|
RakAssert(MINIMUM_LIST_SIZE>=3);
|
|
#endif
|
|
for (listSize=2; listSize < MINIMUM_LIST_SIZE; listSize++)
|
|
{
|
|
readPointer=readPointer->next;
|
|
readPointer->next = RakNet::OP_NEW<DataPlusPtr>( _FILE_AND_LINE_ );
|
|
}
|
|
readPointer->next->next=writePointer; // last to next = start
|
|
readPointer=writePointer;
|
|
readAheadPointer=readPointer;
|
|
writeAheadPointer=writePointer;
|
|
readCount=writeCount=0;
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
SingleProducerConsumer<SingleProducerConsumerType>::~SingleProducerConsumer()
|
|
{
|
|
volatile DataPlusPtr *next;
|
|
readPointer=writeAheadPointer->next;
|
|
while (readPointer!=writeAheadPointer)
|
|
{
|
|
next=readPointer->next;
|
|
RakNet::OP_DELETE((char*) readPointer, _FILE_AND_LINE_);
|
|
readPointer=next;
|
|
}
|
|
RakNet::OP_DELETE((char*) readPointer, _FILE_AND_LINE_);
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
SingleProducerConsumerType* SingleProducerConsumer<SingleProducerConsumerType>::WriteLock( void )
|
|
{
|
|
if (writeAheadPointer->next==readPointer ||
|
|
writeAheadPointer->next->readyToRead==true)
|
|
{
|
|
volatile DataPlusPtr *originalNext=writeAheadPointer->next;
|
|
writeAheadPointer->next=RakNet::OP_NEW<DataPlusPtr>(_FILE_AND_LINE_);
|
|
RakAssert(writeAheadPointer->next);
|
|
writeAheadPointer->next->next=originalNext;
|
|
}
|
|
|
|
volatile DataPlusPtr *last;
|
|
last=writeAheadPointer;
|
|
writeAheadPointer=writeAheadPointer->next;
|
|
|
|
return (SingleProducerConsumerType*) last;
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
void SingleProducerConsumer<SingleProducerConsumerType>::CancelWriteLock( SingleProducerConsumerType* cancelToLocation )
|
|
{
|
|
writeAheadPointer=(DataPlusPtr *)cancelToLocation;
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
void SingleProducerConsumer<SingleProducerConsumerType>::WriteUnlock( void )
|
|
{
|
|
// DataPlusPtr *dataContainer = (DataPlusPtr *)structure;
|
|
|
|
#ifdef _DEBUG
|
|
RakAssert(writePointer->next!=readPointer);
|
|
RakAssert(writePointer!=writeAheadPointer);
|
|
#endif
|
|
|
|
writeCount++;
|
|
// User is done with the data, allow send by updating the write pointer
|
|
writePointer->readyToRead=true;
|
|
writePointer=writePointer->next;
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
SingleProducerConsumerType* SingleProducerConsumer<SingleProducerConsumerType>::ReadLock( void )
|
|
{
|
|
if (readAheadPointer==writePointer ||
|
|
readAheadPointer->readyToRead==false)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
volatile DataPlusPtr *last;
|
|
last=readAheadPointer;
|
|
readAheadPointer=readAheadPointer->next;
|
|
return (SingleProducerConsumerType*)last;
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
void SingleProducerConsumer<SingleProducerConsumerType>::CancelReadLock( SingleProducerConsumerType* cancelToLocation )
|
|
{
|
|
#ifdef _DEBUG
|
|
RakAssert(readPointer!=writePointer);
|
|
#endif
|
|
readAheadPointer=(DataPlusPtr *)cancelToLocation;
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
void SingleProducerConsumer<SingleProducerConsumerType>::ReadUnlock( void )
|
|
{
|
|
#ifdef _DEBUG
|
|
RakAssert(readAheadPointer!=readPointer); // If hits, then called ReadUnlock before ReadLock
|
|
RakAssert(readPointer!=writePointer); // If hits, then called ReadUnlock when Read returns 0
|
|
#endif
|
|
readCount++;
|
|
|
|
// Allow writes to this memory block
|
|
readPointer->readyToRead=false;
|
|
readPointer=readPointer->next;
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
void SingleProducerConsumer<SingleProducerConsumerType>::Clear( void )
|
|
{
|
|
// Shrink the list down to MINIMUM_LIST_SIZE elements
|
|
volatile DataPlusPtr *next;
|
|
writePointer=readPointer->next;
|
|
|
|
int listSize=1;
|
|
next=readPointer->next;
|
|
while (next!=readPointer)
|
|
{
|
|
listSize++;
|
|
next=next->next;
|
|
}
|
|
|
|
while (listSize-- > MINIMUM_LIST_SIZE)
|
|
{
|
|
next=writePointer->next;
|
|
#ifdef _DEBUG
|
|
RakAssert(writePointer!=readPointer);
|
|
#endif
|
|
RakNet::OP_DELETE((char*) writePointer, _FILE_AND_LINE_);
|
|
writePointer=next;
|
|
}
|
|
|
|
readPointer->next=writePointer;
|
|
writePointer=readPointer;
|
|
readAheadPointer=readPointer;
|
|
writeAheadPointer=writePointer;
|
|
readCount=writeCount=0;
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
int SingleProducerConsumer<SingleProducerConsumerType>::Size( void ) const
|
|
{
|
|
return writeCount-readCount;
|
|
}
|
|
|
|
template <class SingleProducerConsumerType>
|
|
bool SingleProducerConsumer<SingleProducerConsumerType>::CheckReadUnlockOrder(const SingleProducerConsumerType* data) const
|
|
{
|
|
return const_cast<const SingleProducerConsumerType *>(&readPointer->object) == data;
|
|
}
|
|
|
|
|
|
template <class SingleProducerConsumerType>
|
|
bool SingleProducerConsumer<SingleProducerConsumerType>::ReadIsLocked(void) const
|
|
{
|
|
return readAheadPointer!=readPointer;
|
|
}
|
|
}
|
|
|
|
#endif
|